The only place i have seen R3J luxeons are the ones that come with Lambda's microilluminator. Short of buying one of those, only other way i can think of getting one is to write a letter to Snata Claus.
The difference between J and K is not much. As I understand it the 3 will be white and the 2 may have a greenish tint. Have you checked any out? How white are they?
RC